Field of the Invention
Embodiments of the present invention are generally related to a system for recycling asphalt millings and methods thereof. More specifically, embodiments of the present invention relate to a system for removing bitumen from the stone found in asphalt millings so that the stone may be recycled and/or reused for future applications.
Description of Related Art
Bituminous concrete, otherwise and more commonly known as asphalt millings, are a common environmental concern during any road construction or similar asphalt construction project. The problem with asphalt millings is that the bitumen binder used in asphalt paving applications contains a relatively large concentration of a family of carcinogenic compounds which can pose serious human health and environmental concerns in certain circumstances such as when asphalt material is ground into very small particles that easily blow off of or wash from the surface.
These compounds, known as polycyclic aromatic hydrocarbons (PAHs) are specified as targeted pollutants by the U.S. Environmental Protection Agency (USEPA), and are present in asphalt at much higher levels than the criteria established by most states for general use in a loose fashion on land. Asphalt millings used alone without a paved top surface have the potential to significantly migrate from the roadway through the actions of water, wind, and physical displacement and possibly contaminate surrounding soils and/or surface water sediments. Traffic traveling on the unpaved asphalt millings would generate dust containing the compounds referenced above and the dust would be a major migration route of the millings to the surrounding environment.
Several uses in of asphalt millings are fully appropriate in accordance with many state's regulations for recycling and beneficial use. However, the use of loose unbound asphalt millings on land and roadway surfaces without the placement of a paved top surface is not generally appropriate; and millings should not be used where runoff to surface water features would be possible in order to prevent sediment contamination. As such, asphalt millings are not considered clean fill.
Many states permit millings may be taken directly to and used by road asphalt manufacturing plants for direct incorporation into asphalt (bituminous concrete), pursuant to recycling exemption for such use which limits the amount of millings per new asphalt that can be used, which can often be 20% or less. As such, for every ton of asphalt millings, there needs to be at least five tons of new asphalt in which to incorporate the millings. Viewed from a different perspective, at least 80% of asphalt bitumen is effectively wasted from reuse due to state environmental restrictions.
As such, there is a need for a system for recycling asphalt millings and methods thereof.